1. Field of the Invention
The invention is in the field of biology, and more specifically in the field of cell biology.
2. Description of the Prior Art
Cell lines, as opposed to cell strains, can be serially cultivated indefinitely. Mammalian cell lines have been established, and the more important ones have been deposited with public repositories such as the American Type Culture Collection (ATCC), Rockville, Md.
Established cell lines have been prepared, however, from only a few cell types; for example fibroblasts, epithelial and lymphoid cell lines are known. None of these have the ability to accumulate fats such as triglycerides. Whereas mammalian tissue contains fat-accumulating cells, known as adipose cells, there has heretofore been no known cell line which displayed a similar characteristic.
Because cell lines did not heretofore exist which accumulated fat in a manner similar to naturally occurring adipose cells, it has been difficult to screen drugs for their effects on fat accumulation. Generally, such tests have been carried out using live animals or in vitro using fatty tissues or fatty cells obtained directly from animals. In the former case, it is difficult to accurately and precisely determine such effects, whereas in the latter case the preparations cannot be cultured, only last for a short time, and cannot be used to test drugs for slow or cumulative effects on fat accumulation such as occur in living animals. The number of drugs which can be tested in severely limited by these factors. Further, cell tissue, once removed from an animal, does not always function in a manner similar to the way it functions in the animal. It can be appreciated, therefore, that such screening of drugs has required considerable work, was relatively expensive to carry out, and has not been as accurate and precise as desired.